Trunions

[Capt Thighbiter]

I;ve seen cannon for sale that are machined as a tube of different sorts and then have the trunions attached in various fashion.

1) trunions sweat fitted into milled pockets

2) trunions sweat fitted into milled pockets and then welded at the joint

3) Trunions JB Welded into milled pockets

4) Trunions welded into milled pockets

5) Trunions threaded and screwed into tapped, flat bottom pockets, then welded.

Milled pockets have flat bottoms ( as opposed to a drilled hole, which has the drill point at the bottom.

Your opinions on these methods?

For the cannon owners among us, how are your trunions attached to your long guns?

I have all bronze guns, with the trunions cast as part of the tube.

[Hawkyns]

All 4 of my cannon were cast solid with the trunnions in place, then bored out and sleeved. They are all iron guns. I don't particularly trust cannon where the trunnions are added after the tube is made. I've seen it done on anything up to six pounders and never been happy with the result. I just don't think that most of the people who are lathe turning guns and then adding things like truniions, or dolphins or even the cascabel are up to the task. Professionals cast them solid and intact. That's the way it's always been done and I don't think this is a place to try and reinvent the whel.

Hawkyns

[Captain Jim]

Any time that you start drilling holes in a tube you weaken the tube so the "added" trunions are always an indication of a weak spot. By far not the best method. It's a shortcut to be avoided. But that wasn't your queation, was it?

Best way to do this is to this is method 5, threaded and welded. And then sleeve the tube to replace the strenth lost in milling the pockets in the first place.

But avoid tubes like this in the first place.

[HarborMaster]

I tried to avoid to this thread for obvious reasons ....., but ., lets talk about this thing.

Castings are weak and brittle ., Yes I have 6 castings and 10 machined barrels. I moved UP to machined after many years of study and learning ., You know when you first get something you cut corners cause you dont know., later you get wiser ? Yea ., me too. You find out about rules ., start reading about PSI testing., Alloys ., Powder tests ., bores ., ect .,

(6) Heat / Cold Interferance fit and bolted into a mill pocket . Machined from superior metals to high tolerances.

Just curious about these comments ? We are talking trunnions from a safety point?

O.K.

Then I must ask what good is your casted (Porous) trunnion when your breach isnt as thick as the bore is large on the most critical point?

The high pressures built are at the breach not the trunnions mid-section ., and recoil is why they have wheels .., to ease recoil on the weapon. Amazing.

This is directed for Mr. Thighbiter. Also sir if you would like to bring this topic up at GBO's Cannon forum where there are actual cannon makers your more than welcome to. After all you are a member there. This is directed at your Wild imports gun. I have one ., I wouldnt use mine at an event where people are present knowing what I know ( and Yes I do know Osvaldo)., so I have filled mine with concrete. I didnt crack on your 385 dollar greystar barrel you got from Tim ., that had a seemed 1/8' water pipe for a liner. I know Tim. Also i didnt crack on you when you tried to sell it to a board member for 900 bux ., but I am cracking now. Lets talk about this at the GBO cannon forum sir where it belongs .

Since we are talking about castings., I am sure Mr. Hawkins knows about NSSA rules and I wont question his cannons ., But I will anyone elses. If your casting is not an original ., then it MUST be X-rayed ., do any of you have X-rays? If not youve got a lawn ornament. You wont be able to live fire at any sanctioned event . Of course you can pop it off at home and risk the lives of your loved ones or on some dock somewhere ., or a ren fair., But Nssa wont allow to risk the public at their event. Live Fire People ., Your talking about trunnions when youve had a greystar and a wild imports cannon ??????? Even the English Gun I am sure has no liner or X-Ray. Without an X-Ray YOU dont know ., neither does anyone else about the porosity of your casting.

I have shared my cannons with board members. Please fellas shed some light on your credentials and your cannons., please let us see some photos of your toys? They did infact re-invent the wheel fellas. The pro's did ., Mr. parrot ., Captain Dalgren ., we've evolved to a machined gun over 100 years ago. Because metals became superior to out dated alloys. the U.S. military is the best ., and theyve re-invented the wheel.

The Mighty mo was a MACHINED cannon firing a 2000 pound projo with 25lb bags of powder .,and your telling me not to trust a machined barrel. I respect you. but not here ., not on this thread and not with these statements. I am very grateful the navy didnt try to fire that projo with all that powder with a casted trunnion ..., what do you think ?

Captain Jim

I will start a thread on broken castings to demonstrate why NSSA wont allow them without propper machined breaches using DOM and X-RAYS . However Machined guns from solid round bar dont need lined or X-Rayed ...., I cant believe you guys dont know this stuff ., yet your commenting with some authority ?????.,Round bar thats about as solid as it gets.., They ARE a liner. Sorry for that rant but I found this thread to be filled with ignorance. Again please state your personal credentials on metalurgy ., cannon construction ., basic dimensional knowledge. And show us your proof of what you say .,pictures are good. Can we see your cannons? I can show mine and already have. There are formula for building ., there is a formula for Breach to bore ., bore to length unless howitzer or mortar (Even a mortar has a bore to length formula. And you got it ., there is trunnion to bore formula. I invite picures of broken machined cannon ., please expand on this phenomenon ., as I am going to start a thread on castings so others can see the importance of being safe ., perhaps it will help educate new cannoneers of safety ., no-kidding.

If you guys already know everything please take no offense ., however if your not to proud hop on over to Greybeard outdoor and join the forum ., there is alot of guys there that are very involved in documenting whats in our inventory as well as saving them all over the country from Bronze disease. research ., creating ., and restoring. Theres alot to learn there. There are experts there . I learn from them and then I do what they tell me .,or I have it done or I go there to ask ., or I write a letter to Mr.Switlik for advice.. If anyone cares to pick up a copy the more complete cannoneer I believe Matt will be releasing his latest revision this spring. Matt Switliks "The more complete cannoneer"is a must read for anyone firing a black powder cannon.

Edited March 10, 2009 by HarborMaster

[Jib]

Jib raises hand and asks the 'stupid' question: Whats a Trunion?

[Capt Thighbiter]

Easy there Harbor Master, I was merely asking for opinions on a methods of construction. I didnt even offer a opinion on what was better or best.

Sounds like someone needs hug!

[Quartermaster James]

Jib raises hand and asks the 'stupid' question: Whats a Trunion?

Main Entry:

trun·nion

Pronunciation:

\ˈtrən-yən\

Function:

noun

Etymology:

French trognon core, stump

Date:

circa 1625

: a pin or pivot on which something can be rotated or tilted ; especially : either of two opposite gudgeons on which a cannon is swiveled

[Graydog]

The items sticking out of the side of the barrel are the trunions. They are used to mount the tube to the carriage and are also the pivot point for elevating/depressing the tube after it's mounted, as in the defintion by Quartermaster James above. Here's an example at number 3 in the diagram (Note I pirated the diagram from the web):

Edited March 12, 2009 by Graydog

[Jib]

Thanks friends!

[Crudbeard]

Thanks friends!

To add a bit of arcainia to the discussion of trunnions, my artillery mentor (used to work for South Bend Replicas) told me that one thing common to cast in sleeves in barrels is that the extra casting metal cooling at cast on trunnions will cause a degree of constriction, or a necking effect in a thin wall sleeve halfway down the bore at the trunnions. This is one reason why more expensive barrels are drilled, and the sleeve pressed and shrunk into the casting. For blank firing purposes this is immaterial really, but in accuracy competiton where the windage of the ball is at a minimum, you could have a problem.

[Littleneckhalfshell]

Ok, Trunions, most cannon have them, though, I suppose you could call a carronade a cannon, but I think they usually don't have Trunions. However in all this talk about cannons, one thing I have not seen mentioned is something else that protrudes from the barrel of a cannon, at least in the older ones i believe, but is rarely seen in reproduction pieces, namely 'Dolphins' does anyone know the time period of their appearance on barrels and when they went out of fashion? Should a cannon of roughly GAOP have Dolphins or not?

Second, again back to Trunions, I was wondering if there is a general rule regarding the placement of Trunions either on the centerline or below the centerline of the barrel? Does this difference in the placement of the Trunions relate to time period, place of manufacture (personal preference) or something else?

[Commodore Swab]

They are placed lower on older guns. Many maunfactures today however place them at the center for a couple of reasons. The first dealing with machined bores (which is that the topic was relating to) is that there is less drilling out of the metal and it is easier whether they are steated, pressed, tapped, or welded in place. When casting using a sand casting it makes it much easier to pull the mold out of the sand, to pull the mold using below center truniuns the truniuns must be verticle and the mold pulled perfectly strait. To place them below center on a lost wax casting is by far the easiest provided you have built the pattern. Currently I work with a friend casting cannons. I have started making my own now that are much smaller. Here is a picture of one of the ones that I'm making:

The largest single pour we have done is a 1700's Howitzer that has also been classified as a center mounted mortar, this casting was done in sand and to give you an idea it was cast with a liner. The liner was composed of the bottom of an 02 cylinder welded to a 6 inch diameter solid bar Firing chamber/breech) that was drilled out for the bore. We required 400 pounds of sand for the mold. To prevent shrinkage of the bronze when it would hit the cold steel there were over 80 pounds of cooling head on the breech as well as the truniuns, requiring 300 pounds of bronze to be melted and poured. Finished the cannon weighs in at roughly 250 pounds.

[Joe Pyrat]

Here are some shots of mortars I got at Castillo de San Marcos in Saint Augustine.

[Capt Thighbiter]

DAM, Vintagesailor, that is NICE lookng mortar!

Correctme if I am wrong but were not mortars always made with trunions on centerline? Its the long guns that

originally had trunions below CL.

[Commodore Swab]

DAM, Vintagesailor, that is NICE lookng mortar!

Correctme if I am wrong but were not mortars always made with trunions on centerline? Its the long guns that

originally had trunions below CL.

When I was refering to below centerline I was refering to long guns, technically a mortar has the truniuns where the cascabel would be. The early mortars with the truniuns mounted in the same location as the long guns were more really really short howitzers. Thanks for the compliment, which one though?

Edited April 9, 2009 by vintagesailor

[the viceroy]

DAM, Vintagesailor, that is NICE lookng mortar!

Correctme if I am wrong but were not mortars always made with trunions on centerline? Its the long guns that

originally had trunions below CL.

When I was refering to below centerline I was refering to long guns, technically a mortar has the truniuns where the cascabel would be. The early mortars with the truniuns mounted in the same location as the long guns were more really really short howitzers. Thanks for the compliment, which one though?

mmmmmm yes nice dutch voc howitzer reproduction if i dont say so my self..........carry on carry on

[Commodore Swab]

mmmmmm yes nice dutch voc howitzer reproduction if i dont say so my self..........carry on carry on

I assume you are refering to the small one

[Capn Bob]

I like trunions...batter dipped and fried, mostly...

What?

We're talking about *cannon*? What does that have to do with a type of small fish?

[Littleneckhalfshell]

I like trunions...batter dipped and fried, mostly...

What?

We're talking about *cannon*? What does that have to do with a type of small fish?

Well, now that you ask, the Trunnions are actually very close to the "Dolphins" (both are in the middle of the cannon)

And of course "Dolphins" are a fish, (not to be confused with the mammal made famous by some guy named Flipper)

Or did you get 'Trunnions' confused with 'Grunions' a sardine sized fish that you do dip in batter and fry, now you made me hungry

Edited April 18, 2009 by Littleneckhalfshell

[William Brand]

mmmmmm yes nice dutch voc howitzer reproduction if i dont say so my self..........carry on carry on

Well, well. The Viceroy. Welcome aboard, sah.

[Capn Bob]

I was hoping someone would pick on the "grunion" direction I was trying to sneakily take this...

I like trunions...batter dipped and fried, mostly...

What?

We're talking about *cannon*? What does that have to do with a type of small fish?

Well, now that you ask, the Trunnions are actually very close to the "Dolphins" (both are in the middle of the cannon)

And of course "Dolphins" are a fish, (not to be confused with the mammal made famous by some guy named Flipper)

Or did you get 'Trunnions' confused with 'Grunions' a sardine sized fish that you do dip in batter and fry, now you made me hungry

[Cannibal Chrispy]

Dolphin is very good batter dipped an' fried too!

[Capn Bob]

Really? Hey, I'll have to try that sometime! Only trouble is, that sort of activity tends to attract the attention of the PETA lubbers...but then, it's been years since I last had any long pig, so that'd work, too...

Dolphin is very good batter dipped an' fried too!